I thought Blackarachnia's progression was logical too and done pretty well - she comes full circle in BM. Silverbolt's character development was progressively logical... just not very well done because of the whole "emo" thing. In Beast Wars we do see that Silverbolt has a bit of a dark side with the capacity for revenge - as seen when he hunted Tarantulas and impaled him when he thought that his Predacon shell program had caused Blackarachnia's death. Silverbolt going through that dark depressive phase was quite understandable - he had been through massive trauma as a Vehicon general... but the problem with that character was, as Scott McNeill put it, it just took him far too long to get over it. Silverbolt turned out pretty nicely in the final eps of Season 2, had that been done a lot sooner then Silverbolt would've been a pretty decent character in that show. So the problem with BM Silverbolt isn't so much that he was illogically developed, but because he spent too long brooding and should've just gotten over his freakin' issues and moved on!